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FONA not connecting AT+CREG 0,3
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

FONA not connecting AT+CREG 0,3

by jpuigdef on Tue Jul 28, 2020 11:57 am

Hi, we operate several fona808, all of them with success except for one that suddenly ceased to connect to the network. When testing it with the FONATest utility, we see that when attempting to connect to the network it starts responding AT+CREG 0,2 (searching) for some time and then it falls into AT+CREG 0,3 (access denied).

The same SIM works fine on other FONA's, and other SIMS (even from other providers) do not change this behaviour.
The CCID of the SIM is correctly read, the battery is fine and works well with other FONAs, and the RSSI signal strength is correct (-78dBm)
We tried to send ATZ, restart, remove batt, etc, without success.

We would appreciate any suggestion on this issue.

Thanks

jpuigdef
 
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Re: FONA not connecting AT+CREG 0,3

by adafruit_support_mike on Thu Jul 30, 2020 12:58 am

Have you tried swapping antennas?

From the list of things that do work, my first suspect would be a weak signal making it impossible for the FONA to finish its authentication with the cell tower. The RSSI only tells you how well the FONA can hear the tower, not how well the tower can hear the FONA.

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Re: FONA not connecting AT+CREG 0,3

by jpuigdef on Thu Jul 30, 2020 5:28 am

thanks Mike,

yes I've tried to swap antennas without success (the antennas were working fine in other fonas in the same location).

I also noticed during one of the trials that RSSI dropped without any apparent reason to -115dBm. Would that mean that de fona hardware itself is failing?

The fona was working fine for some months (october19-april20) and then suddenly ceased to connect.

Thanks
joan

jpuigdef
 
Posts: 37
Joined: Thu May 18, 2017 2:35 pm

Re: FONA not connecting AT+CREG 0,3

by adafruit_support_mike on Fri Jul 31, 2020 4:13 am

It's possible that something in the FONA is starting to go bad, yes. I'm afraid it's outside our 30-day return/replace period though.

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Re: FONA not connecting AT+CREG 0,3

by jpuigdef on Tue May 11, 2021 11:05 am

Hi Mike, again we met two other FONA808 breakouts with the same problem. After some months of fine work, they suddenly stopped transtmitting their data. When testing them we found AT+CREG 0,3. RSSI level was correct and changing the antenna or SIM has no effect. We also tried to reset (ATZ) without success.

Do you have any other suggestion?

Thanks

jpuigdef
 
Posts: 37
Joined: Thu May 18, 2017 2:35 pm

Re: FONA not connecting AT+CREG 0,3

by adafruit_support_mike on Wed May 12, 2021 9:07 pm

Not off the top of my head.

There are hundreds of ways for things to stop working. Debugging is a process of finding a correlation between what doesn't work and something else. Until you can find some common factor between the units that don't work and something in the operating conditions, or some signal whose value is different from the devices that work normally, there's no way to work toward a solution.

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Re: FONA not connecting AT+CREG 0,3

by rskup on Thu May 13, 2021 11:29 am

Hi jpuigdef, just tossing this out there, the 808 is 2G right?, is it possible both boards suddenly coming up "0,3" is indicative of 2G shutting down in your area?

Do you or a friend have an old 2G phone sitting around to test with? Or call your provider and ask about their 2G service in your area?

Might also be worth looking over the AT+COPS command for the 808. I've only used the most basic version of it on my FONA 3G to see what networks are in my area. Here's a link to simcom manuals, the SIM808 folder has an AT manual for the 800, so I guess simcom uses the 800 commands for both chips:

https://simcom.ee/documents/?dir=

If nothing else, you'll find out whether it's really a board problem or whether 2G is no longer available for your area. However, even if you fixed your boards, seems 2G (and 3G) is slowly going away anyways, you might want to consider looking at 4G boards.

rskup
 
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Re: FONA not connecting AT+CREG 0,3

by jpuigdef on Fri May 14, 2021 2:40 am

Thanks, rskup.

We had full 2G coverage in the area. A third FONA808 worked fine.

And yes, we are considering a migration to 4G or other communication systems. Our problem with 4G was its still low dense coverage as compared to 2G in our area

Thanks

jpuigdef
 
Posts: 37
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Re: FONA not connecting AT+CREG 0,3

by rskup on Fri May 14, 2021 8:00 am

Hmmm, interesting.

Wonder if all the units (working and non-working) show the same networks available with the AT+COPS=? command.

Also, don't know if you looked at that COPS command in the 800/808 manual, but there is a variation of it where you can try to "manually" force it to register to one of the available networks listed with the AT+COPS=? command, may be worth a shot.

rskup
 
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Please be positive and constructive with your questions and comments.